Software to upconvert MKV from 576p to 1080p?

[tangledwiring]

Hi. I'm a nature documentary aficionado with a large collection of DVDs and Blu-rays, most of which I have ripped using MakeMKV. Some of my programs come in a shorter Blu-ray version and a longer DVD version. I want to splice the HD footage from the Blu-rays together with the extra footage from the DVDs (I will use MKVToolNix or Avidemux for that), but first all the clips have to be the same resolution. I don't want to downscale the Blu-ray footage because that would defeat the point of having the Blu-rays in the first place. Can anyone recommend a good free or inexpensive program to upscale MKV files from 576p to 1080p? Ideally, it should come with an easy-to-use GUI, because I'm no computer wizard. Thanks!

[LigH.de]

You can find a lot of recommendable video converters, more or less easy to use, like e.g.: StaxRip, MeGUI, Hybrid, Xmedia Recode, Handbrake / VidCoder, ...

But they all are a bit different regarding available features, some even regarding their "engine" (based on AviSynth or VapourSynth as scriptable frameservers, or just ffmpeg as solid framework). The scriptable tools are a bit more flexible, one could add more plugins for more features, which is not easily possible for ffmpeg based tools.

Now there is the main issue of upscaling ... there are so many possible functions to calculate the new resolution, some with more visual "sharpness" but also often with the risk to overshoot and create unwanted ringing artifacts due to the Gibbs phenomenon. There are other "interpolation kernels" with less ringing, but probably also less sharpness (see this kernel visualization in the documentation of ResampleHQ, an AviSynth plugin with more resampling functions).

There are also other approaches to try to upsample video with rather sharp edges, but without boosting unwanted ringing. One method is using "Edge Directed Interpolation", e.g. with the NNEDI3 plugin using a pre-trained neural network, which can upscale the video by powers of 2 (e.g. 2x or 4x the previous size), so you can downscale from there to your target resolution. But this is a very complex project for a user not yet used to manually editing AviSynth scripts. Hardly any GUI converter would offer you such a kind of feature.

In neither way you would restore details lost due to a previously lower resolution. You will only add artifical patterns. Therefore, upscaling is usually only a reason for a lot more bitrate, but hardly conveniently more quality. Before you decide to upscale, be sure that you really need it. Are you sure you may not mix different resolutions? Some authoring techniques may allow to play movies with different attributes in a playlist sequence.

[tangledwiring]

Thanks for the response. I'm not really familiar with "ringing" or "interpolation kernels." Regarding quality, I just want a program that will give me the kind of quality I would get from, say, the Full Screen feature in VLC Player. And I would really prefer the end product to be a single MKV file, not a playlist.

[LigH.de]

The scaling in most video renderers uses a rather simple function, so you will probably be satisfied with any of the tools I mentioned (and the VideoHelp Software archive will offer even more in the "Converters" category). You just need to find one which you can use easily. I believe even Avidemux could scale your video while converting. I guess Xmedia Recode, Handbrake / VidCoder or TEncoder would belong to the simpler GUIs; StaxRip is already more elaborate; MeGUI and Hybrid are rather for the tech-savvy user.

Just be careful, DVDs may contain interlaced content when recorded with TV cameras (or even worse, it was norm-converted from an NTSC production). Check that in scenes with horizontal panning; if you simply upscale and get weavy content in motion, it may have to be deinterlaced first, or resized field-wise.

If you encode your material again after upscaling, to be compatible to Blu-ray, you have to set up not only a Blu-ray compatibility option and Profile@Level matching VBV values, but possibly also enable an interlaced encoding mode in x264, depending on the framerate (e.g. 1080p24 is allowed for Film, but 1080i50 required for PAL rate), even though your video content may be progressive; fortunately, x264 supports a "fake interlace" mode for this purpose: It flags the video output as MBAFF ~ "may be partially interlaced" for Blu-ray compatibility, but will in fact encode progressively and efficiently.